Clock



FIG. 1 is a front view of a clock showing my new design;

FIG. 2 is a top view thereof;

FIG. 3 is a side view taken from the left side of FIG. 1;

FIG. 4 is a side view taken from the right side of FIG. 1;

FIG. 5 is a rear view thereof; and,

FIG. 6 is a bottom view thereof.

The ornamental design for a clock, as shown and described.